This invention relates to a coupling link including first and second half links each having a pair of ears at one end and a tongue at the other end. When the two half links are assembled to form a coupling link the tongue of each link is received within the ears of the other link and retained therein by a link pin which passes through aligned bores formed in the ears and the tongue. More specifically, this invention relates to a means for maintaining the link pins within the aligned bores in the first and second half links.
A coupling link is commonly used to temporarily repair a chain which is broken as a result of a failure of a unitary cast or welded link. Such a coupling link may have a pair of U-shaped half links each having a pair of spaced ears at one end connected by a central body member to a tongue at the other end. When two half links are assembled to form a coupling link the tongue of one link is received between the ears of the other link and a retainer pin is inserted into axially aligned bores in each pair of ears and the mating tongue to join both ends of the first and second half links. The pin must be retained in position to prevent the separation of the first and second half links. Frequently, chains in which coupling links are installed are used in hostile environments such as mining and it is desirable to protect the link pin and the ear and tongue bores from exposure to dirt and mined material as much as possible in order to permit the coupling link to be easily disassembled when it is to be removed from the chain.
One means of retaining a link pin within the ear and tongue bores of a pair of half links is by welding a retainer member over the ends of each of the ear bores. The retainer member limits axial movement of the link pin and helps keep dirt out of the ear and tongue bores. A problem with this retaining means is that it requires welding equipment and a skilled welder whose services are relatively expensive. Additionally, if a chain breaks on a piece of equipment which is inaccessible to or remote from welding equipment, the chain must be removed from the machinery and transported which causes the equipment to be unusable for some period of time.
It is desirable to provide a means for retaining a link pin within the ear and tongue bores of a pair of half links which can be attached to the coupling link without special equipment and without skilled personnel. Additionally, it is desirable that the retaining means protect the ends of the link pin and the ear and tongue bores from dirt and other materials.